1. Field
The present disclosure relates to a control apparatus for an internal combustion engine.
2. Description of the Related Art
Control apparatuses disclosed in Japanese Unexamined Patent Application Publication No. 2005-155469 and Japanese Unexamined Patent Application Publication No. 2014-074337 have hitherto been known as control apparatuses of such a type. In the control apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2005-155469, a basic high octane number fuel ratio is calculated on the basis of the rotation speed and the load of the internal combustion engine. The basic high octane number fuel ratio is the basic value of the ratio in amount of high octane number fuel with respect to the total amount of low octane number fuel and the high octane number fuel, which are to be supplied into a cylinder. In addition, with attention to the fact that knocking of the internal combustion engine is liable to occur with the increasing rate of increase of the load of the internal combustion engine, in order to suppress the knocking, the basic high octane number fuel ratio is subjected to increase correction on the basis of the detected rate of increase of the load of the internal combustion engine to calculate the ratio in amount of the high octane number fuel and the amount of the high octane number fuel to be supplied into the cylinder is controlled on the basis of the calculated ratio in amount of the high octane number fuel.
In the control apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2014-074337, in order to suppress the knocking of the internal combustion engine, the ratio of the amount of high octane number fuel to the amount of low octane number fuel to be supplied into a cylinder is calculated so as to be increased with the increasing load of the internal combustion engine, which is detected, and the amount of the high octane number fuel to be supplied into the cylinder is controlled on the basis of the calculated ratio of the amount of the high octane number fuel. In this case, the amount of the low octane number fuel to be supplied into the cylinder is controlled so that the ratio of the amount of the low octane number fuel to the amount of the high octane number fuel is not decreased to zero even when the load of the internal combustion engine is increased to save the high octane number fuel.